JP2006296084A - Motor drive and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve response upon starting-up a sensor-less driving brushless motor. <P>SOLUTION: A control circuit sequentially moves to six stages (stages 0 to 6) with different energizing patterns at intervals of 2 ms and a motor drive circuit so as to energize a vibrating motor, thus starting the vibrating motor. Moving to the stages permits potentials (U, V and W phases) of motor drive circuit of each motor coil to have voltage waveforms of H-level for three stages, LL-level for the next two stages and a middle potential (Z-level) between the LL level and the H-level. The voltage waveforms have phases shifted by two stages between the respective motor coils. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor drive device that drives a vibration motor, and an electronic device that includes the vibration motor and the motor drive device.

  Mobile phones are equipped with vibration motors that notify incoming calls by vibration. In this vibration motor, an eccentric weight is provided on the rotating shaft of the motor body, and a vibration force is generated by a slight swinging of the eccentric weight when the motor rotates.

  As a vibration motor, a DC motor including a brush and a commutator is also used. However, there is a problem that the sliding contact portion between the brush and the commutator is mechanically worn and the life is shortened by electrolytic corrosion. It is desirable to use a brushless motor.

  As brushless motors, those driven using sensors such as Hall elements are widely used. However, vibration motors mounted on mobile phones are mounted in a housing with limited space. In order to reduce the size, it is desirable to drive the brushless motor sensorlessly.

  In a mobile phone, the vibration motor may be vibrated in accordance with the music of the incoming melody. When such motor drive is performed, if the responsiveness at the time of starting the motor is not good, the incoming melody and the vibration of the vibration motor are shifted, and the occurrence of such a shift can be perceived by the user.

  However, a sensorless drive brushless motor that detects the counter electromotive voltage generated in the motor coil and recognizes the rotational position of the rotor portion has a problem in that it is disadvantageous in terms of responsiveness at the time of activation.

  Accordingly, an object of the present invention is to improve the responsiveness at the start-up for a sensorless drive brushless motor.

  The present invention provides a motor driving device for sensorless driving of a vibration motor that is an inner rotor type three-phase brushless motor in which each motor coil is star-connected, and includes a plurality of switching elements that turn on and off energization of each motor coil. A motor drive circuit, and an activation means for starting the vibration motor by controlling the motor drive circuit so that the vibration motor is energized by sequentially shifting six stages with different energization patterns every predetermined time. And the starting means causes the motor drive circuit side potential of each motor coil to be at the H level for the three stages, the L level for the next two stages, and the next one stage by the stage transition. The voltage waveform has an intermediate potential between the L level and the H level, and the voltage waveform is 2 times between the motor coils. Made to be those whose phases are shifted from each other by chromatography di, it is a motor driving apparatus according to claim.

  When sensorless driving of a vibration motor, which is a brushless motor, among the 6 stages, the voltage waveform on the motor drive circuit side of each motor coil becomes H level for 3 stages and L level for the next 3 stages. In the prior art, the voltage waveform is started so that the phase of the voltage waveform is shifted by two stages between the motor coils.

  However, the potential on the motor drive circuit side of each motor coil is H level for three stages, L level for the next two stages, and an intermediate potential (Z between L level and H level for the next one stage). There is no known technique for starting up such that the voltage waveform becomes a level) and the voltage waveform is shifted by two stages between each motor coil.

  By starting the vibration motor by such energization control of the present invention, the vibration motor can be started smoothly, and the responsiveness at the time of starting the vibration motor can be improved as compared with the prior art. Could be verified (for details, see the examples below).

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic longitudinal sectional view (a) and a schematic transverse sectional view (b) showing a configuration example of a vibration motor targeted by the motor drive device of the present embodiment. In addition, each cutting position of sectional drawing of Fig.1 (a) and sectional drawing of FIG.1 (b) is shown by the AA line and BB line of each figure.

  As shown in FIG. 1B, in the vibration motor 1, the shape of the magnet 2 of the inner rotor portion is in a direction orthogonal to the magnetic pole direction of the anisotropic magnet material oriented in the N / S magnetic field in the radial direction. It is a plate-shaped magnet having a substantially rectangular cross-section in which a non-effective magnetic flux range portion that is positioned is equally cut at both ends. The material composition is preferably a Nd—Fe—B or Sm—Co rare earth magnet. The rare earth magnet is excellent in magnetic properties and can cope with size reduction due to a reduction in diameter. As is clear from FIG. 1B, the magnet 2 itself has a symmetrical cross-sectional shape with respect to the rotation center axis 6, and the rotor portion balance is maintained dynamically.

On the other hand, as a means for unbalance of the rotor portion, the circular portion of the base that has become a substantially rectangular shape of the magnet 2 is separately cut, and one portion that is reduced in weight (that is, one region where the arc is cut off) As a weight inertial body made of a nonmagnetic material having a specific gravity higher than that of the magnet material, a rod-shaped eccentric weight 3 is integrally attached to the magnet 2 as a weight that causes the rotor portion to have an eccentric center of gravity. That is, the center of gravity from the center of the rotation axis of the rotor portion is obtained by attaching the eccentric weight 3 made of a material with high specific gravity to a part of one side of the magnet 2 effective for the eccentric center of gravity while maintaining the magnetic characteristics of the magnet 2 in the small motor. The radius can be increased, and as an inner rotor type vibration motor,
An eccentric rotor portion excellent in space can be configured. The higher the specific gravity of the tungsten alloy is, the closer the specific gravity is to 18.

  A field coil 4 fixedly arranged on the inner wall of the housing case 5 is accurately arranged on the outer periphery of the rotor portion. At this time, as shown in FIG. 1A, the rotor portion includes a bearing 8 on the small diameter portion side where the rotation shaft 6 is narrowed down in the housing case 5 and a bearing on the other end flange 7 of the housing case 5. 8 and is supported by both shafts. At the same time, the support in the thrust direction of the rotor portion is regulated and held by the thrust receiver 9 on the end flange 7 side and the liner 10 on the other side.

  On the other hand, the field coil 4 is fed by a feeding terminal 12 which is a flexible substrate, and the feeding terminal 12 is fixed by a terminal 11. The power supply terminal 12 is connected to a motor drive device 101 (see FIG. 2) described later on the device main body side.

  In this embodiment, the vibration motor 1 is an inner rotor type three-phase brushless motor in which motor coils U, V, and W (described later) are star-connected, and are sensorlessly driven as described later. No sensor is provided.

  The brushless configuration does not have a physical rectification mechanism including a brush and a commutator, and a long-life motor structure is possible. With brushless, due to the characteristics of the motor, there is no concern about mechanical wear and sliding life of the sliding contact part, and there is virtually no wear of the bearing sliding part, that is, the bearing part that supports the rotor part at both ends. The service life of the components is longer than that of the brush and commutator that are the sliding contact portions, and as a result, the reliability of the motor can be improved.

  FIG. 2 is a circuit diagram illustrating a schematic configuration of the motor driving device 101 that drives the vibration motor 1.

  The vibration motor 1 and the motor driving device 101 are mounted on a mobile phone or other electronic device.

  In the vibration motor 1, symbols U, V, and W are three motor coils that are star-connected. Reference symbol C indicates the midpoint (common) of the three motor coils U, V, and W that are star-connected.

  The motor drive device 101 includes a motor drive circuit 102, a control circuit 103, and a microcomputer 104.

  The motor drive circuit 102 is connected to the vibration motor 1 via terminals TU, TV, TW, TC, and has six switching elements SU1, SU2, which turn on and off the energization of the motor coils U, V, W of the vibration motor 1. SV1, SV2, SW1, and SW2 are provided. The switching elements SU1, SU2, SV1, SV2, SW1, and SW2 can be configured by semiconductor switches such as MOSFETs and transistors.

  Switching elements SU1 and SU2 drive motor coil U, switching elements SV1 and SV2 drive motor coil V, and switching elements SW1 and SW2 drive motor coil W, respectively.

  That is, by turning on at least one of the switching elements SU1, SV1, SW1 and any one of the switching elements SU2, SV2, SW2, a current flows from the power source to the motor coils U, V, W, which will be described later. The energization pattern of any of stages 0 to 5 in FIG. 4 can be realized. There are six energization patterns of stages 0 to 5.

  For example, in stage 0 shown in FIG. 4, the U phase is at the H level voltage (V volts (= 3.7 volts, for example)), the V phase is at the L level voltage (0 volts), and the W phase is at the H level voltage (V volts). However, this can be realized by turning on the switching elements SU1, SW1 and SV2. Note that the voltages at the H level, the L level, and the Z level shown in FIG. 4 indicate the potentials of the terminals TU, TV, and TW, respectively.

  In the stage 1, the U phase is the H level voltage (V volts), the V phase is the Z level voltage (1/2 V volts), and the W phase is the L level voltage (0 volts). This is the switching element SU1. And by turning on SW2.

  Reference numerals 111 to 113 denote comparator circuits that serve as position detection circuits for driving the vibration motor 1 in a sensorless manner. Each non-inverting input terminal is connected to the motor coils U, V, and W, and each inverting input terminal is common. C is connected. The rotor portion rotational position of the vibration motor 1 can be determined by detecting the back electromotive voltages generated in the motor coils U, V, and W by the comparator circuits 111 to 113.

  When the magnetic poles (two poles) of the magnet 2 are detected by the respective comparator circuits 111 to 113, the detection signals from any of the comparator circuits 111 to 113 change every 60 ° of the rotation angle of the rotor portion.

  The control circuit 103 outputs the gate signals UH, UL, VH, VL, WH, WL to the switching elements SU1, SU2, SV1, SV2, SW1, SW2, respectively, and controls the motor drive circuit 102. The control circuit 103 can also receive the detection signals from the comparator circuits 111 to 113 and control the motor drive circuit 102 in accordance with the detection signals.

  More specifically, the control circuit 103 outputs gate signals UH, UL, VH, VL, WH, WL to switch on / off of the switching elements SU1, SU2, SV1, SV2, SW1, SW2. The control circuit includes a PWM control circuit that performs PWM control of the vibration motor 1 in accordance with the PWM signal from the microcomputer 104, and the switching circuit is a timer circuit of the microcomputer 104 to be described later and the count time has passed a predetermined time (2 ms to be described later). At this point, the switching elements SU1, SU2, SV1, SV2, SW1, and SW2 are sequentially switched to turn on and off, thereby allowing transition to stages 0 to 5 described later.

  The microcomputer 104 outputs various control signals and causes the control circuit 103 to control the vibration motor 1. In addition, a timer circuit for measuring a predetermined time (2 ms described later) is provided.

  Next, rotation control of the vibration motor 1 performed using the motor drive device 101 having the above circuit configuration will be described.

  FIG. 3 is a flowchart for explaining an outline of the control contents of the vibration motor 1. As shown in FIG. 3, in the rotation control of the vibration motor 1, first, the overlap initial activation is performed for a certain period (step S1). This implements an activation means. Thus, when the vibration motor 1 is started, normal operation is performed (step S2), and the operation of the vibration motor 1 is stopped. The normal operation (step S2) realizes PWM control means, and rotationally drives the vibration motor 1 activated in step S1 by PWM control. Below, the detail of step S1 is demonstrated as an example about the case where the magnetic pole of the magnet 2 is 2 poles.

  FIG. 4 is a flowchart of a subroutine for initial overlap start (step S1). When the vibration motor 1 is started, the six stages (stages 0 to 5) having different energization patterns to the motor coils U, V, and W are sequentially shifted every predetermined time (2 ms in the present example). The drive circuit 102 is controlled.

  Steps S11 to S16 indicate stages 0 to 5, respectively. In stage 0, the potential of the terminal TU is set to the H level, the potential of the terminal TV is set to the L level, and the potential of the terminal TW is set to the H level (step S11). In stage 1, the terminal TU is set at the H level, the terminal TV is set at the Z level, and the terminal TW is set at the L level (step S12). In stage 2, the potential of the terminal TU is set to H level, the potential of the terminal TV is set to H level, and the potential of the terminal TW is set to L level (step S13). In stage 3, the potential of the terminal TU is set to L level, the potential of the terminal TV is set to H level, and the potential of the terminal TW is set to Z level (step S14). In stage 4, the potential of the terminal TU is set to L level, the potential of the terminal TV is set to H level, and the potential of the terminal TW is set to H level (step S15). In stage 5, the terminal TU is set to the Z level, the terminal TV is set to the L level, and the terminal TW is set to the H level (step S16).

  By performing such energization, the voltage waveforms of the U phase (terminal TU), V phase (terminal TV), and W phase (terminal TW) are as shown in FIG.

  In the initial start of overlap, stages 0 to 5 are sequentially shifted every 2 ms, and the condition for shifting from the preceding stage to the next stage is only the passage of time (for example, 2 ms), and is not related to sensorless detection of the rotor unit.

  As shown in FIG. 5, the potential of the U phase (terminal TU), V phase (terminal TV), and W phase (terminal TW) (that is, the potential on the motor drive circuit 102 side of each motor coil U, V, W) is First, for the U phase (terminal TU), the three stages 0 to 2 are at the H level, the next stages 3 and 4 are at the L level, and the next stage 5 is at the Z level. It is a waveform. The V phase (terminal TV) has a waveform shifted by two stages (120 °) from the U phase (terminal TU), and the W phase (terminal TW) has a waveform shifted by two stages (120 °). Such overlap initial activation continues for 12 ms until stages 0 to 5 complete a cycle. By one round of the stages 0 to 5, the rotor part makes one rotation.

  FIG. 6 shows the potential of the U phase (terminal TU), V phase (terminal TV), and W phase (terminal TW) (that is, the motor driving circuit 102 side of each motor coil U, V, W) according to the conventional motor driving device. Potential). As is clear from comparison between FIG. 5 and FIG. 6, the difference between the voltage waveform of the present embodiment and the conventional voltage waveform is that the conventional example uses a general 180 ° energization. In the embodiment, the V phase of the stage 1 (terminal TV), the W phase of the stage 3 (terminal TW), and the U phase of the stage 5 (terminal TU) are at the Z level (all of the conventional examples are at the L level).

  The inventors of the present invention can start the vibration motor 1 smoothly by energizing the vibration motor 1 with the energization pattern as shown in FIG. 5, and the vibration motor 1 can be started more smoothly than in the case of FIG. It was verified that the responsiveness at the time of activation can be improved (details will be described in the examples described later).

  Note that the motor driving device 101 and the vibration motor 1 described above can be mounted on various electronic devices. For example, if the electronic device is a mobile phone, the motor drive device 101 can generate vibrations in accordance with the ringing melody by repeating the processes of steps S1 and S2 of FIG. 3 (in this case, FIG. 3). The microcomputer 104 provides the control circuit 103 with the PWM signal in step S2 at the timing of starting the process. According to the motor drive device 101 of the present embodiment, even when such a method of use is performed, the responsiveness at the time of activation of the vibration motor 1 that is a sensorless drive brushless motor is high. There is no delay, and it is possible to realize high followability of the generated vibration with respect to the incoming melody.

  The present inventors applied a motor driving device 101 to the vibration motor 1 described above and performed a comparative control experiment. Below, the content of this comparative control experiment is demonstrated.

  The experimental results are shown in FIG. In this experiment, the vibration motor 1 is driven by the motor driving device 101 under two different conditions (two patterns of modes 1 and 2), and the start-up performance at the time of starting the motor is compared. Mode 1 shows an embodiment of the present invention, and mode 2 is a conventional example. The magnet 2 has two magnetic poles.

  In FIG. 7, “start-up operation” indicates an operation at the time of start-up of the vibration motor 1 (corresponding to the above-described step S <b> 1). The duty of PWM control at that time is 100%. “2 ms × 6 (1 rotation) 180 ° energization” means that the duration of one stage is “2 ms” and the operation for “6” stages, that is, the motor “1 rotation” is so-called “180 ° energization” "Indicates what has been done. In mode 1, the “special waveform” indicates that the waveform of FIG. 5 described above was used, and in mode 2, the “normal 180 ° energization waveform” indicates the conventional general 180 °. It shows that the energization, that is, the waveform of FIG. 6 described above was used.

  The “normal operation” is the normal operation in step S2, in which the conventional general 120 ° energization is performed with the PWM control duty set to 80%. This normal operation was performed under the same conditions in modes 1 and 2.

  “Change in the number of revolutions” indicates the number of revolutions of each vibration motor 1 when 40 ms, 60 ms, and 90 ms have elapsed since the start of energization.

  “Rise time” indicates the time required for the vibration motor 1 to reach 50% of the rated speed from the start of energization.

  Each data of the measurement result is obtained by capturing the power source current of the power source of the motor drive circuit 102 in an oscilloscope with a current probe in the circuit configuration of FIG. That is, since the power supply current decreases in inverse proportion to the increase in the rotational speed of the vibration motor 1, the time point when the current value becomes an intermediate value (50%) between the starting current and the rated current on the basis of the starting current. It is determined that the point has reached 50% of the rated rotational speed, and the time from the start of energization to the point at which 50% of the rated rotational speed has been reached is the “rise time”. Further, by measuring the period of the voltage output waveform of the terminal TU (or terminal TV or TW) when 40 ms, 60 ms, and 90 ms have elapsed since the start of energization, the “change in the number of revolutions” can be measured.

  Each result of modes 1 and 2 in FIG. 7 shows the average value of the measured values for three times, and the raw data in the number of measurements 1 to 3 in each mode 1 and 2 is shown in FIG.

  As can be seen from the result of FIG. 7, the “rise time” in mode 2 requires 59 msec, whereas the “rise time” in mode 1 is reduced to 54 msec. It can be seen that the “time” was reduced by about 10%.

  As described above, it was verified that the “rise time” can be shortened as compared with the conventional case by using the mode 1 shown in FIG. 5 for the energization pattern to the vibration motor 1.

It is the schematic longitudinal cross-sectional view (a) and schematic cross-sectional view (b) which show one structural example of the vibration motor which the motor drive device of one Embodiment of this invention makes object. It is a circuit diagram of the motor drive device of this embodiment. It is a flowchart explaining the outline | summary of the control content of the vibration motor by a motor drive device. It is a flowchart explaining the subroutine of overlap initial starting. It is a timing chart explaining starting of a vibration motor by overlap initial starting. It is a timing chart explaining starting of the conventional vibration motor. It is explanatory drawing which shows the result of the comparison object experiment of an Example. It is explanatory drawing which shows the data of each measurement frequency in the result of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibration motor 101 Motor drive device 102 Motor drive circuit SU1, SU2, SV1, SV2, SW1, SW2 Switching element U, V, W Motor coil

Claims (3)

In a motor drive device for sensorless driving of a vibration motor that is an inner rotor type three-phase brushless motor in which each motor coil is star-connected,
A motor drive circuit comprising a plurality of switching elements for turning on and off energization of each motor coil;
Starting means for starting the vibration motor by controlling the motor drive circuit to sequentially shift six stages with different energization patterns every predetermined time to energize the vibration motor;
With
The starter moves the stage so that the motor drive circuit side potential of each motor coil is at the H level for three stages, the L level for the next two stages, and the L level for the next one stage. And a voltage waveform having an intermediate potential between the H level and the voltage waveform, and the voltage waveform is shifted in phase by two stages between the motor coils.
The motor drive device characterized by the above-mentioned.   The motor drive device according to claim 1, further comprising PWM control means for controlling the motor drive circuit and performing PWM control on the vibration motor after the vibration motor is started by the start means. In electronic equipment,
A vibration motor that is an inner rotor type three-phase brushless motor in which each motor coil is star-connected;
The motor driving device according to claim 1 or 2, which drives the vibration motor;
An electronic device comprising:

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